1. Field of the Invention
The present invention relates to a reading apparatus for reading an image of a document.
2. Description of the Related Art
There is known a reading apparatus which reads an image of a document while relatively moving the document and an image sensor. One type is a flatbed scanner (abbreviated to FBS in the present specification) which performs scanning while moving an image sensor (line sensor) with respect to a document fixed on a document positioning plate. Another type is a sheet-through scanner which performs scanning while moving a document with respect to a fixed image sensor (line sensor). A unit which moves sheets of the document while separating the sheets one by one is referred to as an auto document feeder (abbreviated to ADF in the present specification).
Japanese Patent Application Laid-Open No. 2009-246665 discusses a reading apparatus that combines the above two types. The apparatus discussed in Japanese Patent Application Laid-Open No. 2009-246665 can read an image in a movement at a constant speed and can also read the image in a movement at an accelerating or decelerating speed.
In such a reading apparatus, a read-suspension event may occur during the reading of the document. Examples of the event may be as follows:
(1) There is a limitation to the capacity of a buffer memory which temporarily stores data output from a line sensor before the data is transmitted to a main storage unit. There may be considered a mode for temporarily suspending the reading and waiting until an empty space is provided in the buffer memory when the capacity of the buffer memory is to become full. This is one example of the read-suspension event.(2) If the reading is continued in succession for a long time, heat generation of a motor serving as a movement driving source is increased. In order to prevent the motor from being overheated beyond an allowable level, there may be considered a mode for waiting for temperature drop of the motor by temporarily suspending the reading or a mode for suppressing an excessive temperature rise by performing an intermittent operation. This is another example of the read-suspension event.